Fusion OS is a Open Source Operating System, mainly licensed under the MPL 1.1. Parts of it are licensed upder the GNU GPL or other open source licenses.
Fusion OS is based on the ReactOS project, and we contribute any bugs found in ReactOS back to them

Perix is a free public domain MS-DOS compatible operating system written in Turbo Pascal and Assembly. Multi tasking, parallel data transfer and extended memory support. All parts of system are distributed under terms of the GNU license.